Cutting mechanism for bread wrapping machines



Dec. 25, I w HQPPE ET L CUTTING MECHANISM FOR BREAD WRAPPING MACHINES Filed Nov. 23, 1932 INVENTOR Mum/v flbPPE Mo 1162mm ZZZ r0 WEE m E Patented Dec. 25, 1934 MEGHANISM FOR BREAD WRAPPING MACHINES CUTTING William Hoppe and Norman woliyon; Springfield, A Mass, assignors to NationalBreadWrapping Machine 00., Springfield, Mass, a corporation of Massachusetts Application November 23, 1932. Serial No. 644,066

13 Claims.

' This invention relates to cutting mechanism particularly adapted for the web supply of a wrapping machine such as is used for enveloping bread.

--One object of the invention is to provide a cutting mechanism having a great rapidity of cut so that it may be employed in cutting aweb in motion without the necessity of causing travel of the cutting mechanism in the direction of motion of the web. Another objectis to provide a cutting mechanism which will operate upon-the free end I of a web without the necessity of maintaining the web under tension or of carrying it upon a continuous support. Another object is to provide an improved cam mechanism for operating such a cutting device which will operate with great rapidity without causing a substantial amount of shock at the end of the cutting stroke. Additional objects will appear from the following description and claims. i i Referring to the drawing: i I

Fig, 1 is a side elevation, partlyin section, of a cutting mechanism embodying the invention; Fig. 2 is a smaller view showing theparts in a different position of operation; .Fig. 3 is a top plan view of a portion of the mechanism shown in Fig. 1; and i i Fig. i is a section on line;44 of Fig. 3.

.The mechanism is shown as being supported upon a frame held together with suitable tie bars 11. Cutter bearing arms 12 and 13 are journaled upon a shaft 14 running transversely of the direction of travel of the web to be severed, as will appear more clearly below. This shaft is it preferably fixed to one of the members, the other being mounted for free rotation upon it- These :arms 12 and 13 are shown as having the same axis, but if desired they could obviously beprcvided with separate supports which would-not necessarily bev in exact axial alignment. .The arm 12 carries near its end a cutter blade 15, while the arm 13 carries a block 16 and anend piece 1'7 spaced apart so as to form'between them a slot into which the cutter may pass. These cuttem are oscillated from the position of Fig. l to that of Fig. 2 by the mechanism to be described below, the two cutters'meeting at substantially the plane of the paper web w. By reason of the provision of .thedouble members lii and 17 on the 1 arm 13, a support is given to the web throughout its width, this support being sufiicient to enable the web to be severed without the necessity of maintaining it under tension. 1

The arm 12 is pivoted at 18 to a link 19. This link is in turn pivoted at 20 to an arm 21 swinging freely upon a'supporting shaft 22 mounted uponthe frame. The arm 13 has a rearward extension to which is pivoted at 23 a link 24, also coupled to the pivot 20. Upon'the arm 21 is mounted a cam. roll 25 held against the surface of a cam 26 by a tension spring 27 stretched between the arm 21 and a pin on the frame; The cam'26 is mounted upon a shaft 23 and is rotated continuously by any suitable mechanism. Upon the shaft is a sleeve 29 carrying a pivot 30 having its axis eccentric to the axis of the shaft 28. A curved link 31 joins this pivot with the supporting shaft of the roll 25. As the cam revolves, the roll 25 will drop oif theshoulder 50, forcing the pivot 30 downwardly as viewed in Fig.1. pivot moves downwardly. it is carried underneath the shaft 28 by the necessary rotating movement of thesleeve 29, and as it swings underneath the shaft the sleeve acts like a crank approaching dead center, bringing the link 31 and consequently the roll 25 andits attached parts to rest without jar and with'a smoothly decelerated movement.

By the mechanism described the closing movement of the cutting members will be started with fair rapidity and will i be terminated with a smoothness not foundin the-customary drop-off cam mechanism. It is an additional feature of the present'invention that the normal speed of acceleration of thefdrop-ofi cam is increased, this being possible-without subjecting the mechanism to undue strain-on account of the smooth deceleration due to -the pivot 30'. It is a.recognized difliculty with drop-bif 'carn mechanisms that where a cam roll is used to avoid friction the speed of drop-oif is greatly reduced on account of the factthat the roll rolls over the edge of the drop-off'shoulder and does not dropsharp- 1y over it; To avoid this defect in the present case,a block 34 is mountedupon-the arm 21 in a positionlso that itnormally does not make contact with the surface of the cam 26, being held just away from its surface by the roll 25. As the roll 25 passes' over the shoulder 50, however,

the block 34 is brought to rest upon the cam surface allowing the roller to pass oifthe shoulder without producing any. substantial movement of the arm 21. No movement of this arm other than the slightone necessary to bring the block 34 into contact with the cam surface occurs until the block itself passes over the shoulder. Since the block and the shoulder can both be made with straight sides, the shoulder being even undercut if desired, the block isfreed substantially instantaneously. Thespeed of acceleration toward the As the i 'ment 33 on the link 31.

axis of the cam may be made as high as desired by increasing the strength of the spring 27.

The web to is drawn over the stationary paper support 35 and under the guide 36 which is carried upon arms 37. These arms are pivoted upon a transverse shaft 38 carried upon the ends of arms 39 which in turn swing upon a stationary pivot shaft 40. The guide arms 3'7 have rearward extensions 41 connected by a stop rod 42 adapted to determine the lowermost position of the guide 36 by its contact with the undersides of arms 39. The guide 36 can, however, be raised manually if desired to assist in threading the paper. Running in gaps in the paper support are a plurality of free rolls 43 above which are rubber rolls 44 carried upon the shaft 38, previously referred to. The web is in this case intended to be drawn out by a series of grippers upon a chain indicated at 45, the rolls 43 and 44 acting merely to hold the leading end of the web in position after severance. In order to grip the web tightly upon severance the rubber rolls 44 are clamped by stopping the rotation of shaft 38. To do this a grooved roll 46 is mounted upon its shaft in position to be contacted with by a grooved pad 47 carried upon an arm 48 swinging freely upon the transverse shaft 40. An extension 49 of this arm lies above a cam 50 carried by the shaft 14 and oscillated by this shaft as it turns with one of the cutting members.

The operation of the device will now be considered. Although the particular form of web feeding mechanism is not of importance it may be assumed that the web w is being drawn out by a continuously moving gripper upon the chain 45. While the web is traveling the roll approaches the shoulder 50 and in passing over its edge lowers the block 34 against the cam surface. The slight movement of the cutters involved in this action is without significance. When the block 34 passes over the shoulder 50 the spring 2'7 causes a rapid movement of the cam follower towards the axis of the cam, accelerating the cutting members very rapidly toward the closed position shown in Fig. 2. As they approach the moving web they are moving with sufiicient rapidity to form a clean out completely across the web, allowing the severed sheet to continue its movement with the grippers and removing the tractive force of the grippers from any influence uponthe body of the web. At the same timethe clamp 46-47 operates to hold the leading end of the web body firmly in position. In spite of the great rapidity with which the cutting members are closed, they are decelerated with equal rapidity and without shock by the passage of the pivot underneath the shaft 28. Due to this construction, a much stronger spring 27 and a much sharper drop-off of the cam can be used than with a construction in which the closing movement of the cutters were to be interrupted merely by contact'of the cam follower with the reduced portion of the cam. In the present case the portion of the cam below the shoulder is preferably cut away so that neither the roll 25 nor the block 34 strike it,the entire burden of stopping the movement of the cam follower being borne by the pivot 30. The pivot 30 is thus left in a dead center position and it is pref erable to provide mechanism for at least initiating its return to the position of Fig. 1. In the present case this is done by a pin 32 on the cam 26, positioned to contact with a slanting abut- Contact between these members moves the pivot 30 to the left in Fig. 2 and positions the partsso that the follower may be raised to its normal position by coaction between the cam surface and the roll 25.

What we claim is:

1. Web severing devices comprising a pair of cutter members pivoted upon substantially coincident axes extending across the web, one of the members having spaced portions forming a slot between them into which the other member is adapted to pass, and means for oscillating the cutter members simultaneously in opposite directions upon paths intersecting the line of travel of the web at substantially right angles, so that the cutting edge of one member passes into the slot in the other at the plane of the web and with a motion substantially normal thereto.

2. A cam mechanism for web severing mechanism and the like, comprising a drop off cam, a cam follower riding on the cam, a pivot mounted for rotation about an axis substantially coincident with the axis of the cam, and a link connecting the cam follower with the pivot to control the motion of the follower upon its release by the cam.

3. A cam mechanism for web severing mechanism and the like, comprising a drop off cam, a cam follower riding on the cam, a spring drawing the cam follower towards the cam to impart a quickly accelerated motion to the follower upon its release by the cam, a pivot mounted for rotation about an axis substantially coincident with the axis of the cam, and a link connecting the cam follower with the pivot to control the motion of the follower upon its release by the cam and to bring it to rest with a smoothdeceleration.

4. A cam mechanism for web severing mechanism and the like, comprising a drop off cam, a cam follower riding on the cam, a spring drawing the cam follower towards the cam to impart a quickly accelerated motion to the follower upon its release by the cam, a shaft carrying the cam, a member mounted for free rotation upon the shaft, va pivot carried upon the member eccentric with respect to the shaft, and a link connecting the pivot to the follower, the parts being so proportioned that upon the release of the follower by the cam the line joining the pivot and the shaft is at a substantial angle to the line joining the pivot with the follower, the pivot swinging around to the side of the shaft remote from the follower and opposing a progressively increasing resistance to the motion of the follower whereby the follower is decelerated smoothly and is brought to rest without shock.

5. A cam mechanism for web severing mechanism and the like, comprising a rotatable drop off cam, a cam follower comprising a roll and a bar trailing behind the roll and adapted to bear against the cam only when the roll starts over the drop off shoulder and to drop with great suddenness over the shoulder when the shoulder has completely passed the roll.

6. A cam mechanism for web severing mechanism and the like, comprising a rotatable drop off cam, a cam follower comprising a roll and a block trailing behind the roll and adapted to bear against the cam only when the roll starts over the drop off shoulder and to drop with great suddenness over the shoulder when the shoulder has completely passed the roll, a pivot mounted for rotation about an axis substantially coincident with the axis of the cam, and a link connecting the cam follower with the pivot to control the motion of the follower upon its release by the cam.

*7. A cam mechanism for web severing mechanism and the like, comprising a rotatable drop off cam, a cam follower comprising a roll and a block trailing behind the roll and adapted to bear against the cam only when the roll starts over the drop off shoulder and to drop with great suddenness over the shoulder when the shoulder has completely passed the roll, a spring drawing the cam follower towards the cam, a rotatable shaft carrying the cam, a sleeve mounted for.

free rotation upon the shaft, a pivot carried upon the sleeve eccentric with respect to the shaft, and

a link connecting the pivot to the follower, the

parts being so proportioned that upon the passage of the block over the shoulder the line joining the pivot and the shaft is at a substantial angle to the line joining the pivot with the follower, the pivot swinging around to the side of the shaft remote from the follower and opposing a progressively increasing resistance to the motion of the follower whereby the follower is decelerated.

smoothly and is brought to rest without shock.

8. Web severing mechanism comprising a pair of cutter members pivoted upon axes extending across the web, a rotatable drop off cam, a cam follower riding on the cam, links connecting the cam follower with the cutter members at points respectively on opposite sides of their pivots, a pivot mounted for rotation about an axis substantially coincident with the axis of the cam, a link connecting the cam follower with the pivot to control the motion of the follower upon its release by the cam, and a spring drawing the follower towards the cam, the parts beingso proportioned that upon the passage of the follower over the shoulder of the cam the line joining the lastnamed pivot and the cam shaft is at a substantial angle to the line joining said pivot with the follower, the pivot swinging around to the side of the shaft remote from the follower, whereby said cutting members will be accelerated rapidly from their separated positions towards a position in which their cutting edges pass at the plane of the web, and will be decelerated smoothly and stopped in that position without shock.

9. Web severing mechanism comprising a pair of cutter members extending across the web, a rotatable drop off cam, a cam follower comprising a roll and a block trailing behind the roll and adapted to bear against the cam only when the roll starts over the drop off shoulder of the cam and to drop with great suddenness over the shoulder when the shoulder has completely passed the roll, links connecting the cam follower with the cutter members at points respectively on opposite sides of their pivots, a shaft carrying the cam, a member rotatable upon the shaft and bearing a pivot eccentric with respect to the shaft, a link connecting the cam follower with the last-named pivot, and a spring drawing the cam follower towards the cam, the parts being so proportioned that upon the passage of the block over the 'shoul-.

der of the cam the line joining the last-named pivot and the cam shaft is at a substantial angle to the line joining said pivot with the follower,

whereby no substantial resistance is offered to the rapid acceleration by the spring of the follower smoothly and brought to rest without shock with their cutting edges passing at the plane of the web.

10. A cam mechanism for web severing mechanism and the like comprising a rotatable drop off cam, a follower riding on the cam, a spring drawing the cam follower towards the cam to impart a quickly accelerated motion to the follower upon its release by the cam, a shaft carrying the cam, a member carried upon the shaft eccentric with respect to the shaft, a link connecting the pivot to the follower, the parts being so proportioned that upon the release of the follower by the cam the line joining the pivot and the shaft is at a substantial angle to the line joining the pivot with the follower, whereby no substantial resistance is offered to the rapid acceleration of the follower by the spring, the pivot swinging around to the side of the shaft remote from the follower whereby the follower will be decelerated smoothly and brought to rest without shock, and means for initiating the return of the pivot back to its original position.

11. A cam mechanism for web severing mechanism and the like comprising a rotatable drop off cam, a follower riding on the cam, a spring drawing the cam follower towards the cam to impart a quickly accelerated motion to the follower upon its release by the cam, a shaft carrying the cam, a member carried upon the shaft eccentric with respect to the shaft, a link connecting the pivot to the follower, the parts being so proportioned that upon the release of the follower by the cam the line joining the pivot and the shaft is at a substantial angle to the line joining the pivot with the follower, whereby no substantial resistance is offered to the rapid acceleration of the follower by the spring, the pivot swinging around to the side of the shaft remote from the follower whereby the follower will be decelerated smoothly and brought to rest without shock, and a pin on the cam, and a slanting abutment on the link acted onby the pin to initiate the return of the pivot back to its original position.

12. Mechanism for severing a moving web comprising a pair of cutting members movable towards each other from opposite sides of the web, a spring urging the members together, means operative to release said members at a definite point in the cycle for free acceleration towards each other under the force of the spring, and positive means for decelerating the members with a substantially harmonic motion so that they are brought rapidly but smoothly to rest at a predetermined position.

13. Operating mechanism for web severing mechanism of the type in which the severing mechanism is given its web severing motion by a spring, comprising a quick release device for permitting the spring to accelerate the severing mechanism, and a rigid linkage connected to the severing mechanism and having its parts proportioned and arranged to permit substantially free movement of the severing mechanism by the spring at the instant of release and to decelerate the severing mechanism positively and rapidly and with a substantially harmonic motion so that it is brought smoothly to rest at a position predetermined by said linkage. 

